1. Field of the Invention
The present invention pertains to endoscopic surgical instruments and, more particularly, to a valve assembly for providing a variable size passage in an endoscopic portal to prevent fluid flow through the valve while allowing surgical implements of various sizes to be selectively introduced through the valve.
2. Description of the Prior Art
Surgical procedures involving the placement of an endoscopic portal, such as a sleeve or cannula, through a body wall to provide a passage for insertion of surgical instruments frequently require that the passage be sealed to prevent the flow of fluids through the endoscopic portal. For example, many medical procedures gain access to the interior of an anatomical cavity by utilizing a surgical puncturing or penetrating instrument, such as a trocar, obturator or needle, having a sharp penetrating point for puncturing or penetrating the cavity wall to establish communication with the interior of the anatomical cavity. A sleeve or cannula is then left in situ for utilization as a portal to introduce surgical instruments into the anatomical cavity. Because it is necessary to prevent fluid flow to and from the surgical site, the portal must be sealed prior to and subsequent to the introduction of surgical instruments and while such instruments are in place. Furthermore, fluids, such as gaseous phase carbon dioxide or nitrous oxide, may be introduced into the anatomical cavity for insufflation as part of the surgical procedure, and the escape of the gas must be prevented during puncturing and during the endoscopic surgical procedure. Typically, surgical instruments are inserted into the portal via a valve that has a single, particular size passage dependent upon the puncturing instrument. However, additional instruments to be introduced into the anatomical cavity through the passage may be of diverse types and sizes, and it will be appreciated that fluid can escape past smaller instruments.
A surgical puncturing instrument is usually received within a portal sleeve that passes through the wall of an anatomical cavity with the puncturing instrument and remains in place to establish communication with the interior of the cavity after the puncturing instrument has been removed from the sleeve. The sleeve typically has a proximal end secured in a housing provided with a valve that allows the puncturing instrument to be inserted into the sleeve. The valve prevents the flow of fluids to and from the anatomical cavity and closes when the puncturing instrument is removed from the sleeve. The size of the puncturing instrument utilized varies depending upon the surgical procedure and the type of anatomical cavity to be punctured. Once the puncturing instrument has been removed from the sleeve, a great variety of instruments of various sizes and diameters are introduced into the anatomical cavity via the portal dependent upon the procedure to be performed.
Prior art endoscopic portals utilize a valve, such as a flapper or gate valve, that is normally biased to a closed position but in an open position has a passage or lumen therethrough of only a single size. Accordingly, such endoscopic portals suffer from the disadvantages of allowing the passage or leakage of fluids when surgical instruments smaller than the single passage are introduced therethrough or of limiting the implements to be used in a procedure to a single size. Additionally, such endoscopic portals can be effectively used with only a single size puncturing instrument.